Il A heavy ball with a weicht of 100 N (m 10.2 kg) is hung. from the ceiling of a lecture hall on a 4.5-m-long rope. The ball. is pulled to one side and released to swing as a pendulum, reach-. ing a speed of 5.5 m/s as it passes throuoh the lowest point.
Inventions. The huochong gun was invented in China during the Ming dynasty. It was also called the tongjiangjun, which meant bronze general. This was an important invention of the time period because the Ming Dynasty was creating weapons to defend their dynasty, and they came across the gun.t was also called the tongjiangjun, which meant bronze general. This was an important invention of the time period because the Ming Dynasty was creating weapons to defend their dynasty, and they came across the gun.
Gunpowder was the first physical explosive and propellant. Prior to its invention, many incendiary and burning devices had been used, including Greek fire. The invention of gunpowder is usually attributed to Chinese alchemy, and is popularly listed as one of the .Four Great Inventions  of China.It was invented during the Tang Dynasty (9th century), and the earliest record of a written formula appeared in the Song Dynasty (11th century).Knowledge of gunpowder spread throughout the Old World as a result of the Mongol conquests of the 13th century.t was invented during the Tang Dynasty (9th century), and the earliest record of a written formula appeared in the Song Dynasty (11th century). Knowledge of gunpowder spread throughout the Old World as a result of the Mongol conquests of the 13th century.